Field of the Invention
Embodiments described herein generally relate to an apparatus and methods for reducing the deposition of polymers in a semiconductor processing chamber. More specifically, embodiments described herein relate to enhanced productivity for an etch system through polymer management.
Description of the Related Art
Plasma chambers may be utilized in certain substrate etching processes. These chambers generally include an RF inductive coil positioned on a backside of a dome or roof of the chamber overlying a substrate being processed. An RF power source may be connected to the coil to couple inductive energy into the chamber to create a plasma source region remote from the substrate being processed.
A recurring problem with chamber walls and dome is that, even in an etching environment, residue may form on the walls and dome resulting from byproducts of the etching process. Such byproducts may be photoresist layers or other materials which are removed from the substrate. The byproducts may be in a gaseous or solid phase and may deposit on the walls of the chamber and the dome. In addition to the byproducts, certain etch chemistries may use polymerizing reactive gases to enhance sidewall protection for certain types of features (i.e. via or trench) being etched on the substrate. The polymerizing reactive gases may also deposit on the internal surfaces, such as the walls or dome, in the vicinity of the plasma.
The residue adhering to the chamber walls and dome may flake off and fall into a processing area of the chamber. Any such particle that falls onto the substrate is likely to produce a failure or reliability problem in the integrated circuit being fabricated on the substrate. If a ceramic dome is used, which acts as a dielectric window for coil antennas, the particle problem may be exacerbated. A source coil is intended to couple large amounts of energy into the chamber and hence, is often operated at high power levels. Inevitably, a substantial fraction of RF energy is thermally dissipated in the dome.
However, the coil is only intermittently operated as substrates are cycled into and out of the chamber, and a ceramic is generally a poor thermal conductor. As a result, the dome material is subjected to repeated and significant temperature swings, resulting in repetitive cycles of thermal expansion and contraction of the dome. The thermal effects are largest in the areas immediately adjacent to the coil. Under these conditions, the residue is more likely to flake and produce particles.
As previously described, residue on the walls or dome during etching is generally undesirable. The residue can be disruptive to system performance and the resulting on-substrate results. One method to manage the residue is to periodically replace the dome. However, this method is very expensive and time consuming. Another method of managing the residue is to clean the chamber interior. However, this method imposes significant system downtime and requires manual involvement of technicians.
Accordingly, what is needed in the art is an apparatus and method for reducing or controlling polymer deposition in a substrate processing chamber in a timely and cost efficient manner that decreases processing chamber downtime.